This application claims priority to Japanese Patent Application Nos. 2010-262188, filed Nov. 25, 2010 and 2011-245215, filed Nov. 9, 2011, the entirety of which is incorporated herein by reference.
1. Technical Field
The present invention relates to a liquid discharging apparatus and a liquid discharging method.
2. Related Art
There is known a liquid discharge apparatus that records images or the like by discharging liquid from a nozzle such that droplets (dots) are landed onto a medium. When performing recording using this kind of liquid discharge apparatus, it is not always possible to discharge dots to the desired discharge positions due to errors in the nozzle accuracy of the nozzle which are caused in the manufacturing stage. As a result, density irregularity (for example, white stripes or black stripes) is generated in the recorded image and the image quality of the recorded image is deteriorated.
There is a method of making discharge errors unrecognizable and reducing the visibility of density irregularity by forming one dot line by several-time discharge operations, using different nozzles. For example, there has been a method of suppressing deterioration of an image quality by averaging the deviation of landing positions of dots, by respectively changing the nozzles that discharge liquid in a liquid discharge operation on a going-path and a liquid discharge operation on a returning-path, in a liquid discharge apparatus that forms dot lines in the reciprocation direction by discharging the liquid while reciprocating the nozzles.
There is a method of adjusting the timing of discharging liquid, as a method of suppressing density irregularity or disarray in an image due to a conveying error of a recording target medium. For example, a method of forming inclined dot lines and suppressing deterioration of an image, when a medium is conveyed at an angle by skew, by shifting the nozzles discharging the liquid in accordance with the inclination is suggested (For example, JP-A-2007-144946).
According to the method described above, it is possible to reduce the visibility of the influence of density irregularity, even though density irregularity is generated when an image is recorded by a liquid discharge apparatus. However, when an error in accuracy of the nozzle is large, for example, when the gap between the n-th nozzle and the n+1-th nozzle is remarkably large in comparison to the gaps between other nozzles in the nozzle lines, it is difficult to reduce the visibility of the influence of the density irregularity in the method. This is because the striped density irregularity is visible at the portion with the large gap between the nozzles, even if the nozzles used in the going-path and the returning-path are changed. As described above, it is difficult to sufficiently reduce the visibility of the density irregularity invisible in the method of the related art.